A wireless tag includes an antenna and a circuit chip electrically connected to the antenna. The antenna includes an inductance section and a dipole section. The inductance section performs impedance matching with the circuit chip. The impedance matching is performed by approximating a radiation resistance value of the antenna with respect to the capacitance of the circuit chip, and resonating the inductance of the antenna and the capacitance of the circuit chip.
Japanese Laid-open Patent Publication No. 2006-268090 discloses a technique of a tag-use antenna.